Device for testing electrical circuits



May 6, l1952 H. c. GRANT, JR., ETAL 2,595,245

DEVICE FOR TESTING ELECTRICAL CIRCUITS Original Filed April l0, 1943 2 SHEETS-SI-IEET 1 May 6, 1952 y H. c. GRAN-r, JR., ETAL 2,595,246

DEVICE FOR TESTING ELECTRICAL CIRCUITS 2 SHEETS-SHEET 2 Original Filed April lO, 1945 www Patented May 6, 1952 UNITED STATES PATENT OFFICE 2,595,246 DEVICE Fon TESTING ELECTRICAL CIRCUITS Original application April 10, 1943, Serial No. 482,572. Divided and this application January 27, 1948, Serial No. 4,636

Claims. (Cl. 177-329) The present invention relates to a device for testing an electrical circuit to determine that it is in working order prior to the occurrence of an eIl'lElgellCy.

This application is a division of our copending application Serial No. 482,572, filed April 10, 1943, new Patent No. 2,448,026, dated August 31, 1948.

More particularly, the invention relates to a device for testing a circuit having one or more detecting devices therein provided with circuit closing elements which are rendered effective in response to flame, predetermined high temperatures, or upon submersion of the devices in an electrically conductive liquid such as salt water. Such detecting devices may be installed in airplanes or other craft or vehicles and maybe employed to effect operation of an alarm or signal indicating that a state of emergency exists. If desired, the circuit may be utilized, in addition, to eiiect operation of systems for combating the emergency. For example, in response to heat or ame, a lire extinguishing system may be operated; and, in response to submersion in salt water, suitable airplane iiotation gear may be operated.

The present invention aims to provide a device for testing a detecting circuit of the foregoing character whereby to determine if any of the circuit closing elements are in circuit closing position or are short circuited. The invention further aims to provide a device for testing the circuit having indicating means which in turn may be tested.

Accordingly, an object of the invention is to provide a simple testing device which is readily connected 'in the circuit.

Another object is to provide a simple, compact device for testing the circuit, which may be installed on the dash board or control panel of a craft or vehicle. i

Another object is to provide a circuit testing A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:

Figure 1 is a wiring diagram of an electrical circuit of the character to be tested by the device of the present invention.

Figure 2 is a front elevational View of a circuit testing device made in accordance with the invention. f d

Figure 3 is a sectional view taken substantially along the line 3 3 on Figure 2.

Figure 4 is a rear View of the device shown in Figures 2 and 3, avcasing thereof being indicated in section to show interior parts in elevation.

Figure 5 is a sectional View of a circuit testing device illustrating a modied embodiment of the invention, together with a partial wiring diagram for the device.

Referring to the drawings, and more particularly to Figure l, there is shown a circuit for detecting flame or predetermined high temperatures. A series of detecting devices I0 are connected in the circuit, as about to be described,

' each of which comprises a pair of circuit closing device having indicating means responsive to elements I I and I I' each adapted to bridge a pair of contacts or terminals l2 and I4, and I2 and I4', respectively. The terminals I2 of the elements II are connected to one side or line I5 of the circuit, while the terminals I2 of the elements II are connected to the other side or line I6. The terminals I4 of the elements II and the terminals I4 of the elements II are connected to common terminal means or line I1 for the purpose to be described hereinafter.

The circuit closing elements II and II normally are held in open circuit position but are permitted to bridge their respective contacts in response to ame or high temperature. By providing a pair of circuit closing elements for each detecting device IIJ, arranged in series, both elements must `bridge their contacts or terminals to close the circuit. This prevents premature operation of the detecting circuit in the event one of the circuit closing elements is permitted to bridge its contacts due to some mechanical defect.

Suitable thermo-responsive detecting devices adapted to be used in the circuit disclosed herein are illustrated in Patent Number 2,318,607, granted May 1l, 1943. y

A device ZI) for testing the circuit, will rst be described with reference to its electricalconnections and'its relation to the detecting circuit as shown in Figure 1. Generally, the device 20 comprises a pair of indicating devices, and a pair .of

switches so connected to each other and in the circuit that it is possible to determine whether or not the indicating devices are in working order, whether or not an element II or II is in its circuit closing position; or in the event one of the detecting devices has been operated due to flame or high temperature causing its elements Il and II to close the circuit by connecting lines I5 and I6.

The indicating devices may be lamps 2i and 22 connected in parallel with respect to each other and in series with respect to the circuit between terminals 24 and 25. The switches 26 and 21 may be of the normally open circuit push button type, and are connected in series with respect to each other between terminals 25 and 29. The lamps and switches are operatively connected in the circuit by connecting one side of the detecting circuit or line I to the terminal 29, connecting the other side of the detecting circuit or line IE to the terminal 25, and connecting the common line i1 of the detecting circuit between the switches 2S and 21 at 35. In order to provide a source of electrical energy and to complete the circuit, one pole of a battery 3l is connected to the terminal 24 and the other pole of the battery is connected to the terminal 2S. If desired one pole of the battery may be grounded and terminal 24 or terminal 29 may be grounded.

In operating the testing device to determine whether or not the lamps are in working order, both switches 26 and 21 are closed simultaneously. Current will iiow from one pole of the battery to the terminal 24, will divide and pass through the lamps to the terminal 25, will ow through the closed switches 26 and 21 to the terminal 29, and will return to the other pole of the battery. If the lamps are in working order, they will light. A defective lamp will not light and hence can be detected and replaced.

In order to detect that one of the elements II is in circuit closing position, the switch 21 is closed. Current will flow from one pole of the battery to the terminal 24, through the lamps to the terminal 25, through the switch 21 to the common line I'I and across the contacts I2 and I4 which are closed by their element I I, through the line I5 to the terminal 29, and to the other pole of the battery. Both lamps will light giving an indication that one of the elements II is in circuit closing position.

In order to detect that one of the elements Il'` is in circuit closing position, the switch 26 is closed. Current will flow from one pole of the battery to the terminal 2d, through the lamps to the terminal 25, through the line I6 and across the contacts i2 and Id which are closed by their element ll', through the common line I1 to30, through the switch 26 to terminal 29, and to the other pole of the battery. Both lamps will light giving an indication that one of the elements II is in circuit closing position` In the event that an element I I or II is found to be in circuit closing position it is placed in open circuit position or the faulty detecting device is replaced by one having its elements in proper open circuit position.

The foregoing tests usually are made preparatory to the flight of a plane or before sending a land vehicle, such as an armored tank, into action.

In addition to serving as a circuit testing device, the device 2l) is adapted'to indicate when a pair of elements I I and I I' engage their respec-l tive contacts I2 and I4, and I2' and I4 andl 4 thereby close the detecting circuit. Should this occur, with both of the switches and 21 open, current will flow from one pole of the battery to the terminal 22, through the lamps to the terminal 25, through the line I6 and across the ele- -ments II and Il in circuit closing position to Athe line I5, through the line I5 to the terminal 29,

and to the other pole of the battery. Both lamps will light automatically indicating that the detecting system has been operated.

It will be understood that operation of a fire extinguishing system or other emergency system could be effected automatically by the detecting circuit, or that upon automatic lighting of the lamps such a system could be operated manually.

In Figures 2, 3 and 4, a practical embodiment of a testing device 2Q is illustrated. The device is in the form of a compact unit comprising a supporting member, such as a mounting plate a unit 35 secured to the mounting plate having a pair of sockets 31 and 38 for the lamps 2l and 22, respectively, which extend outwardly through suitable openings in the mounting plate (Figure 3); and a unit 39 secured to the mounting plate and housing the switches 2B and 21 which are operated by push buttons d@ and 4I, respectively, urged outwardly through suitable apertures in the mounting plate by resilient means 42 (Figure 3).

The switches, sockets and lamps are electrically connected by conductors in the manner illustrated in the wiring diagram, Figure 1, and more particularly as shown in Figure 4. For example, a conductor 45 connects the sockets 31 and 38, which are in electrical contact with one side of the lamps 2l and 22, respectively, to the terminal 24, and conductors and t1 connect the other side of the lamps 2l and 22, respectively, to the terminal 25. The switches 26 and 21, respectively, close the circuit between the terminals 29 and 25 and a conductor 48 having the line I1 connected thereto at 38.

A box or casing 5i), a section of which is removed in Figure 4, is secured to the back of the mounting plate 3.5 for housing the socket and switch units 36 and 3i?. If desired, the box 5B may be secured to the structure of the craft or vehicle on which the testing device 2B is used.

A suitable panel 5I, preferably, is superimposed upon the front of the mounting plate and is detachably secured thereto. The panel is provided with apertures through which the push buttons lil and 4I extend, and is provided with a protective casing portion 52 for housing the exposed ends of the lamps 2l and 22. By being detachably secured, the panel 5I may be readily removed to facilitate replacement of the lamps.

The panel 5I, preferably, is formed of a translucent plastic molding composition of the cellulose acetate type or the like, so that the lamps, when illuminated, can be readily seen through the casing portion 52. If desired, the walls of the casing portion may be thinner than the other portions of the panel to render it more translucent; The panel can be readily molded and may vbe provided with suitable legend or indicia.

In Figure 5, a modified testing deviceZB' is illustrated which generally comprises a mounting plate 35', a panel 5| on the front of the mounting plate, and sleeves 54 and 55 secured to the back of the mounting plate for facilitating compact assembly of push buttons, lamps, lamp sockets and switch contacts, as aboutto be described.

The sleeves 5i and 55 have assembled therewith lamp sockets 31' and 38' slidably mounted in the sleeves at the ends secured to the mounting plate 35'. Lamps 2| and 22' are mounted in the sockets and have one of their contacts 56 extending through the sockets. Suitable hollow cap-like push buttons 40' and 4I' are secured to sockets 31 and 38', respectively, and extend outwardly from the front of the device through apertures provided in the mounting plate 35' and the panel 5 I The push buttons house the lamps and are formed of translucent material to permit the lamps to be seen therethrough when they are illuminated.

The contacts 56 of the lamps are engaged by one end of contact pins 51 and 51' slidably mounted in the sleeves. Preferably, one end of each of the pins is supported by a disc 58 and the other end of each of the pins is slidably supported in a bushing 59 secured in the corresponding sleeve 54 or 55. A spring 60 is' mounted on each of the pins, intermediate the disc 58 and the bushing 59. These springs are adapted to urge the pins into contact with the contact 56 of the lamp. The ends of the sleeves opposite the ends secured to the mounting plate have bushings 6I secured therein supporting contact members 62 and 62', respectively.

The foregoing described elements are assembled in the sleeve 55, so that the pin 51 is adapted to engage the contact member 62 when the push button 4I' is moved inwardly toward the sleeve 55, the pin 51' being moved toward the contact member by the contact 56 of the lamp 2 2' movable with the push button 4I'.

In order to provide an electrical circuit, about to be described, the elements are assembled in the sleeve 54 so that the pin 51 does not contact the contact member 62 to close an electrical circuit. Preferably, the pin 51 moves or carries another member insulated from the pin which engages the contact member 62 to close a circuit. This may be accomplished by slidably mounting a second pin 65 in the sleeve 54 having one end supported by a disc 66 and having its other end slidably supported by a bushing 61 secured in the sleeve 54. The pin 65 is normally held out of engagement with the contact member 62 by a spring 69 mounted on the pin between the discs 66 and the bushing 61. The spring 69 urges the pin 65 toward the pin 51, but a disc 16 of insulating material prevents electrical contact between the pins 51 and 65. When the push button 48' is moved inwardly toward the sleeve 54, the lamp contact56 moves the pin 51 which in turn moves the pin 65.

The device 26 is adapted to be electrically connected in a circuit corresponding to the circuit illustrated in Figure 1 and described in connection therewith. To accomplish this, the lamps 2l and 22' are connected in parallel between terminals 24' and 25 by connecting together one contact of each lamp and connecting together the pinsk 51 and 51 which are in electrical connection with the other contact 56 of the respective lamps. The terminal 24' has one side of a battery 3l connected thereto and the terminal 25' (which is in electrical connection with the pins 51 and 51') has a line I6' of the detecting circuit (not shown) connected thereto.

The pin 65 and the -contact member 62 provide a switch 26', and the pin 51' and the contact member 62' provide a switch 21'. The switches 26' and 21' are connected in series by connecting the contact members 62 and 62'. The common line I1' of the detecting circuit is connected between the switches 26 and 21' at 30'. The line I5 of the detecting circuit is connected to the terminal 29' which is connected to the pin 65 and to the other side'of the battery 3 I The operation of the testing device 20' is substantially the same as the operation of the device 20 described herein. The lamps 2I' and 22' may be testedby pushing the buttons 40' and 4I' inwardly at the same time. This causes the pins 65 and 51' to engage their respective contact members 62 and 62 whereby the lamp circuit is closed, starting from one side of the battery 3| to the terminal ,-2,4', through the lamps to their contacts 56 `which engage pins 51 and 51', l.through switches 21' and 26' to the pin 65, to terminal 29 and to the other side of the battery. If the lamps are in working order, they will both be illuminated.

vIn order to determine whether or not a circuit is closed between lines I5' and I1', the button 4I' is pushed inwardly. In the event the circuit is closed between lines I5' and I1', a -circuit will be completed through the lamps,starting from one side of the battery 3I' to the terminal 24', through the lamps to the terminal 25', through switch 21', which is-closed, -to the line I1', and across to the line I5', connected to the other side of the battery by way of terminal 29'.

In 'order to determine whether or not a circuit is closed between lines I6' and I1', the button 40 is pushed inwardly. In the event the circuit is closed between lines I6' and I1', a circuit will be completed through the lamps, starting from one side of the battery 5I' to the terminal 24', through the lamps to the terminal 25 and line I6', across to line I1', through switch 26', which is closed, to terminal 29' and back to the other side of the battery.

In the event electrical contact is established between lines I5 and I6', a circuit will be completed through the lamps. starting from one side of the battery 3|' to the terminal 24', through the lamps to the terminal 25' and to line I6', across to line I5 to terminal 29', and back to the other side of the battery.

In view of the foregoing description, it will be seen that the present invention provides a simple testing device for an electrical circuit. The testing device is compact in arrangement and sturdy in construction and is readily used for testing a number of conditions which may exist in the circuit. In'addition, the testing device serves as a visualalarm in the event the occurrence of an emergency sets off the detecting circuit. By combining the lamps with the push button assembly, the size and weight of the device may be further reduced.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacricing any of its advantages, it is to be understood that all matter herein isto be interpreted as illustrative and not in any limiting sense.v

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

We claim:

1. A device of the class described comprising a mounting plate, a panel mounted on said plate having a hollow translucent portion projecting outwardly at the front thereof and having an aperture therein, and a switch and lamp assembly mounted in back of said panel including a switch operating push button extending forwardly through the aperture of said panel and a socket in back of said hollow portion and in alignment therewith for mounting a lamp havinga portion thereof disposed in said hollow portion whereby the lamp when illuminated is visible through said hollow portion.

2. A device according to claim l, wherein the hollow portion is integrally formed with said panel and is of a reduced thickness.

3. A device of the class described comprising a mounting plate having a pair of apertures, a

panel mounted in front of saidplate having a4 hollow, translucent forwardly projecting portion in alignment with one of said plate apertures and having an aperture in alignment with the other of said plate apertures, and a switch and lamp assembly mounted in back of said plate including a switch operating push button extending forwardly through said aligned plate and panel apertures and including a socket in alignment with said hollow portion for mounting a lamp adapted to extend through said plate and into said hollow portion whereby the lamp when illuminated is visible through said hollow portion.

4. A device of the class described comprising a mounting plate, a panel mounted on said plate having a hollow translucent portion projecting outwardly at the front thereof and having a pair of apertures adjacent said portion, and a switch and lamp assembly including a pair of switch operating push buttons each extending forwardly through one of said panel apertures and including a pair of sockets for mounting lamps positioned tc extend into said hollow portion, whereby the lamps when illuminated are visible through said hollow portion.

5. A device of the class described comprising a mounting plate having opening means and a pair of apertures adjacent said opening means, a panel formed of translucent material mounted in front of said plate having an integrally formed hollow forwardly projecting portion of reduced thickness positioned over said opening means and having a pair of apertures in alignment with said pair of plate apertures, and a switch and lamp assembly mounted in back of said plate including a pair of switch operating push buttons each extending forwardly through one of said aligned plate and panel apertures and including a pair of sockets for mounting lamps positioned to extend through said plate opening means and into said hollow portion, whereby the lamps when i1- luminated are visible through said hollow portion.

HARRY C. GRANT, JR. ARTHUR W. UHL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Num *er Name Date 2,014,592 Schwarze Sept. 17, 1935 2,195,975 Ribble et al. Apr. 2, 194() 2,355,149 De Giers Aug. 8, 1944 2,448,026 Grant Aug. 31, 1948 

